Systems are available for providing selective shading for solar greenhouses and the like. In one known arrangement, a shade is transferred from one motor-driven roller towards a second motor-driven roller by straps which are fastened to the leading edge of a shade, these straps being attached to one of the rollers and being wound upon the same to draw the shade from the other roller upon which the shade is coiled and normally stored. In addition, the leading edge of the shade is provided in the form of a rigid member, the edges of which are guided in a channel provided in a guiding member which has no structural function and is intended solely for the purpose of being a shade guide.
An inspection of the available system reveals that the leading rigid element of the aforegoing system extends laterally beyond the lateral edges of the shade so that the lateral edges of the shade are spaced from the guide and thus provide means for an inadvertent passage of solar radiation or the like between the guides and the shade edges. It is also to be noted that the guides have no structural function to be performed as has been noted hereinabove, and that the guides are generally mounted inwardly of the solar greenhouse structure in such a manner as to be readily receptive of inadvertent damaging forces or the like. Moreoever, it will be noted that the shade is inconveniently positioned with its lateral edges subject to damage and deterioration.
Also previously available are shades having lateral edges into which are incorporated wires or cables or the like which give to these lateral edges a conformation which is bulbous in nature. These bulbous lateral edges are accommodated in guiding tracks which heretofore have been exclusively rectilinear and solely vertically disposed. These shades have not been incorporated into solar greenhouses or other such complex structures for purposes of providing selective shielding or shading.
Additionally available are rollers within which are provided internal motors of generally cylindrical conformation. These motors are utilized for selectively driving the associated rollers for taking up straps attached to shades or for rewinding shades and the like. Insofar as known, these motor-driven rollers have not been utilized in conjunction with structural members of solar greenhouses or the like in the manner which will be described in greater detail hereinbelow.
In copending application Ser. No. 455,475 referred to above, there is disclosed an arrangement in which two motor-driven rollers are employed for the selective drawing out of and taking up of a shade. Such an arrangement is useful but is more expensive and requires more electrical wiring than is necessary in the arrangement to be shown hereinbelow.